microbe-tree-80PULLMAN, Wash. – Under a tiny Christmas tree in an engineering building on the Washington State University campus sits a questionable “gift” – a muddy bucket of water with a “Happy Holidays” greeting.

The lights decorating the tree actually “plug into” that five-gallon bucket, pulling energy from a microbial fuel cell (MFC) that sits in water from a local stream and sediment.

“The microbial fuel cell could power lights for a full-size tree – we just don’t have the room for that,” says Haluk Beyenal, associate professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering.

In addition to the muddy water, the bucket contains two electrodes, a few wires and dedicated crews of bacteria doing what they do best – eating.

The system is essentially a large, slimy version of a battery. As the bacteria eat, they release electrons that flow from an electrode buried in the sediment to one closer to the surface, generating electricity.

These microbes are quick eaters, too. Food is at their cell-tips so they can release electrons constantly, generating enough energy to activate the lights every 500-600 milliseconds.

Beyenal and his graduate student Timothy Ewing set up the microbial fuel cell in the hall about two years ago as a form of outreach. They hoped the blinking lights, which spell out “MFC” during the rest of the year, would prompt students to ask questions about the unique alternative energy source in a bucket.

Beyenal’s 2010 National Science Foundation CAREER award helped fund the outreach.

Microbial fuel cells generate a low amount of power that is consistent and continuous, giving them many underwater and remote power applications. Powering something that requires a lot of energy, like a sleigh, is probably not an option.

Ewing is researching the use of MFCs to power machines that aerate water in treatment plants where bacteria have a constant supply of organic material to consume. He is specifically interested in capturing electrons more efficiently, which will help development of other useful microbial fuel cell applications.

Researchers can simulate continuous conditions in the lab by using river or waste treatment water and replenishing organic materials periodically. Systems that Beyenal set up in his lab four years ago are still generating energy.

While the fuel cell in Dana Hall does not have an endless supply of food, it has been powering the string of lights continuously for about two years and will likely light up a miniature tree for several Christmases to come.



Haluk Beyenal, WSU College of Engineering and Architecture, 509-335-6607, beyenal@wsu.edu

Alyssa Patrick, WSU College of Engineering and Architecture communication, 509-335-8067, apatrick12@wsu.edu